When an inflated tire carries a load, the major part of the load is supported by the air inside the tire. A lesser, but not negligible part, is carried by the tire structure itself. When the tire is operated in underinflated conditions, the air ceases to contribute to load carrying, and the entire load rests on the tire structure. Self-supporting tires are designed with a reinforced structure able to carry the entire load under deflated/underinflated conditions. A major contributor in obtaining the required structure stiffness is the sidewall, whose bending properties largely influence the tire's run-flat potential, and, more particularly the reinforcement of the sidewall that allows the tire to carry a greater load.
Through the use of high wheel camber and toe angles, car suspensions are often designed in such a way that the load carried by a tire is not equally distributed between the inner and outer side of the tire. Given the fact that both sides of a tire are generally equal, this causes an asymmetric loading of the footprint leading to a side-to-side non-uniform shape that can be detrimental to the tire performance. This becomes particularly important in the case of a deflated self-supporting tire. In other words, it is inherent to current design practice that one of the two sides of a self-supporting tire is generally overdesigned in terms of bending stiffness.
To offset the positive camber of a tire, it has been proposed by Ranik, Jr in U.S. Pat. No. 4,203,481 to increase the bulk of the sidewall insert on the side of the tire designed to be mounted on the inside of the vehicle by at least 25% over the bulk of the insert on the opposing side of the tire. Ranik also teaches the use of an asymmetric rim with the asymmetric self-supporting tire.
The present application shows alternative ways to create a desired asymmetry in a cured tire to achieve a rebalancing for the asymmetric loading condition during partly or fully deflated service conditions.